1. Field of the Invention
This invention is related to an elastic multi-layer film, and more particularly, to an elastic multi-layer film comprising a thermoplastic polyurethane and a grafted polymer, and to an article thereof.
2. Description of the Prior Art
The thermoplastic elastomer, the so-called TPE, or the thermoplastic rubber, the so-called TPR, is frequently used as elastic thin film material for the plastic processing maker. In the field of the processing application, other physical properties in addition to the elasticity of the elastic thin film are also important, which can determine whether it can be developed successfully or not. In other words, good elastic thin films need to have not only the sufficient elasticity but also other necessary physical properties, so as to satisfy the request of the application.
From the application of the shoe materials, lots of research studies focus on shoe-pad formed by elastic thin film materials. For example, U.S. Pat. No. 5,756,195 and U.S. Pat. No. 7,685,744 disclosed a shoe-pad material respectively, comprising a cloth and SEBS (styrene/ethylene/butylene/styrene copolymer) gel. In addition, U.S. Pat. No. 4,666,782 also disclosed a sulfured rubber utilized for shoe-pad and comprising thermoplastic polyurethane (TPU) and 15 wt % polyether, which provides the oil resistant and anti-crack properties. The U.S. Pat. No. 5,542,196 disclosed another shoe-pad applicable material, which is a thermoplastic elastomer made by thermoplastic polyurethane and vinyl acetate copolymer.
However, current elastic thin film materials still exhibit many disadvantages. For example, a conventional method for manufacturing the shoe-pad by thermoplastic rubber is using a solvent type adhesive to adhere the cloth and the thermoplastic rubber. However, during lamination the solvent based adhesive spreads the toxic gas and undesired residue, which are very difficult to handle. Therefore, there is a need to provide a novel elastic thin film material that can solve the conventional problem.